This invention relates generally to inflator devices such as used in vehicular safety restraint installations and, more particularly, to inflator devices such as desirably reduce, minimize and/or avoid moisture communication to moisture sensitive contents thereof.
Inflator devices such as used in vehicular safety restraint installations commonly employ gas generant materials which, upon actuation by an initiator device, desirably react or otherwise produce or form gas, such as may be used to inflate an inflatable airbag cushion or bag. Such gas generant materials are commonly formed as a tablet or other gas generant body having a predetermined shape and size. As will be appreciated, the selected shape and size of a gas generant material body can desirably be varied to provide a particular surface area, as the surface of a gas generant body can provide a convenient means of control over the rate of production of gas upon reaction of the gas generant material. Various gas generant materials, however, are known to be moisture sensitive. In view thereof, it is desirable that associated inflator devices store or contain such gas generant materials in a sealed or airtight chamber.
In addition, various gas generant material forms or bodies, such as tablets, for example, have been known to be prone to chipping or otherwise undesirably breaking, such as, for example, during assembly of the inflator device or upon actuation of the initiator, which can undesirably increase surface area and have an undesirable effect on the rate of gas production. In addition, it is known to coat various gas generant material bodies, such as tablets, for example, with an igniter material such as to increase the rate of gas production. Chipping and breaking of such igniter material coated gas generant material bodies can have an undesirable effect on the performance and use of such coated gas generant bodies.
Initiator assemblies are known for use in joining an initiator to an inflator device housing. Initiator assemblies known in the art are often used to seal the inflator device storage chamber containing the gas generant material at one end. Recent initiator assemblies include an injection molded adaptor formed around the initiator. Injection molded adaptors, such as typically formed at least in part by a thermoplastic material, can provide significant advantages both in manufacture and in reducing costs. Unfortunately, however, some thermoplastic materials are known to absorb and transmit moisture. Moreover, although the rate of moisture transmission through specific thermoplastic materials may be relatively low, over the design life or term of use common for inflator devices such as used in vehicular inflatable restraint systems, even such relatively low rates of moisture transmission can have detrimental effects on the performance of at least certain gas generant materials and the inflator devices which include or contain such gas generant materials.
In view of the above, there remains a continuing need and a demand for improvements in inflator devices. In particular, there remains a need and a demand for improvements in inflator devices whereby moisture transmission from an initiator assembly to the supply of gas generant material contained within the inflator device is desirably reduced, minimized or otherwise prevented or avoided.